Synchronous-type circuit breaker having two independently-operable mechanisms

ABSTRACT

A fluid amplifier is utilized to operate the secondary or synchronous contacts of a circuit breaker having main or nonsynchronous contacts and secondary or synchronous contacts, which are connected in parallel-circuit relation when the breaker is closed. The operation of the fluid amplifier is controlled by repulsion coil actuated valves. The energization of the repulsion coils is so controlled by current responsive means and by a synchronous control device that the secondary contacts are opened just prior to a current zero after the opening of the main contacts of the breaker. Compressed gas stored in an accumulator supplies energy for open-reclose-open-reclose operation of the secondary contacts if necessary.

United States Patent 1151 3,660,625 Allen, Jr. 1 1 May 2, 1972 54] SYNCHRONOUS-TYPE CIRCUIT 3,486,517 12/1969 Gaura 137/815 BREAKER HAVING TWO 3,526,243 9/1970 Warnemuende et al. ...200/81 FA UX gigigfg FOREIGN PATENTS OR APPLICATIONS 1,149,772 6/1963 Germany ..200/148 J [72] Inventor: Laird R. Allen, Jr., Monroeville, Pa.

. i Primary Exan1inerRobert K. Schaefer [73] Assignee. Westinghouse Electric Corporation, Pitt- I Assistant Examiner Roben A. vanderhye Sburgh AttrneyA. T. Stratton, Clement L. McHale and Willard R. 22 Filed: Jan. 23, 1970 Crow [21] Appl. No.: 5,180 [57] ABSTRACT A fluid amplifier is utilized to operate the secondary or J, 2 B, Z /D synchronous contacts of a circuit breaker having main or non- 137/81.5 synchronous contacts and secondary or synchronous contacts, [51] Int. Cl ..Fl5c 3/02, l-iOlh 33/30 which are connected in parallel-circuit relation when the [58] Field of Search ..200/81 FA, 82 B, 148 J, 148 E; breaker is closed. The operation of the fluid amplifier is con- 137/815 trolled by repulsion coil actuated valves. The energization of the repulsion coils is so controlled by current responsive 56] References Cited means and by a synchronouscontrol device that the secondary contacts are opened just prior to a current zero after the open- UNITED STATES PATENTS ing of the main contacts of the breaker. Compressed gas stored in an accumulator supplies energy for open-reclose- 2,920,170 1/1960 Caswell B X: open reclose Operation ofthe secondary contacts necessary 3,105,126 9/1963 Peek et a1. ..200/82 B 3,267,947 8/1966 Bowles ..l37/8l.5

Claims, 3 Drawing Figures I I l 36 I 76 14 x h 13? E&\ U 47 L1 74 IIIIIII 48 F 2787 lo D 620 F m v 1 18 P CK 72 HEATER STRAINER E 67 CONTROL CH 66 I 7| l6 73 MAIN I9 ACCUMULATOR OIL W 3 RESERVOIR J PATENTEDMAY 2 I972 3. 660,625

SHEET 1 UF 2 [a uumllll P CK HEATER CONTROL STRA'NER PRESSURE SWI , 73 M IN A ACCUMULATOR 9 OIL RESERVOIR PATENTEDMAY 21912 3, 660. 625

- sum 2 OF 2 TO TO ACTUATOR ACTUATOR FIG. 2

WITNESSES INVENTOR X/JWW MW Lolr-d R. Allen, Jr.

Mai w ATTORNEY SYNCIIRONOUS-TYPE CIRCUIT BREAKER HAVING TWO 'INDEPENDENTLY-OPERABLE MECHANISMS BACKGROUND OF THE INVENTION This invention relates, generally, to circuit breaker operating mechanisms and, more particularly, to fluid-actuated mechanisms for operating circuit breakers having synchronously operated contacts which are opened just prior to a current'zero-of an alternating current wave.

ln us. PatfNo. 3,390,240, issued June 25, 1968 to R. R.

Circle and T.O.Pi'unty, and' assignedto Westinghouse Electric and controlledby'a valve operated by a synchronous operator.

SUMMARY OF THE INVENTION In accordance with the invention, the secondary or synchronous contacts of a circuit breaker are operated by a fluid amplifier "having a reciprocating piston which actuates the moving secondary contact'member. The operation of the fluid amplifier is controlled by repulsion coil actuated valves. The energization of the repulsion coils is so controlled by current responsive means and by asynchronous control device that the secondary contacts are opened justprior to a current zero after the opening of the main contacts of the breaker. Compressed 'gas stored in an accumulator in the fluid amplifier supplies energy foropen-reclose-open-reclose operation of the secondary contacts if the current is not interrupted at the first current zero.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and particularly to FIG. 1, the circuit breaker shown therein is generally of the type described in the aforesaid US. Pat. No. 3,390,240. One pole or phase of thecircuit breaker is shown. Additional poles, similar to the one shown, may be provided for multi-phase power systems. The circuit breaker structure shown comprises a housing 10, terminal bushings 11 and 12 mounted on the housing 10, main or non-synchronous contact means 13, secondary or synchronous contact means 1'4, fluid amplifier means 15 for operating the secondary contact means 14, a fluid reservoir 16, a motor 17 for driving a pressure producing means or pump 18, a'nda main accumulator 19. The reservoir 16, motor 17, pump 18 and accumulator 19 may be utilized for supplying fluid pressure to all pole units of a multi-phase breaker. A check valve CV is provided in the line between the pump 18 and the main accumulator 19.

The main contact means 13 includes a relatively movable non-synchronous contact member 20, a relatively stationary contact finger assembly 21, an orifice member 22 having an arcing ring 23 disposed in a generally cylindrical throat 24 of the orifice member, a contact finger assembly 25 slidably engaging the movable contact member 20, and an insulating member 26 having one end attached to the movable member 20 and the other end connected to a suitable'first operating mechanism D (not shown) which may be of a type well known in the circuit breaker art. The generally cylindrical contact member 20 passes through the throat 24 to engage the base of a generally cup-shaped member 27 movably disposed in the finger assembly 21. The finger assembly 25 is mounted in an insulating body member 28 and the assembly 25 is electrically connected to a portion 29 of the terminal bushing 12. The cup-shaped member 27 is biased outwardly in the finger assembly 21 by a compression spring 31. The finger assembly 21 is electrically connected to a conductor 32 which, in turn, is connected to a portion 33 of the terminal bushing 11.

The main non-synchronous contact members. are of a relatively heavy construction. Thus, when the movable contact member 20 is closed to engagethe'member 27 and then the fingers 21, a current path having a relatively low resistance and low voltage drop is provided through the circuit breaker from the terminal bushing 11 to the terminal bushing 12. The bushings 11 and 12 may be connected to suitable power conductors. 1

The secondary contact means 14 includes a relatively stationary contact finger assembly 34 and a generally cylindrical movable contact member 35 having an enlarged end portion which engages a cylindrical stationary contact member 36 which is connected to the conductor 32. The finger assembly 34 is connected to the arcing ring 23 by a conductor 37 and a primary winding 38 of a transformer 39 having a secondary winding 41. The function of the transformer 39 will be explained more fully hereinafter. y v i As explained hereinbefore, the secondary contact means 14 is connected in parallel-circuit relation with the main contact means 13 when the circuit breaker is closed. The secondary contact members maybe of a relatively light construction since they do not carry the continuous or load current of the circuit breaker, the major portion of which flows through the main contact members which are of a relatively heavy construction. However, when the main contact members are partly opened, with the member 20 separated from the member 27, but still engaging the arcing ring 23, and the secondary contact members are closed, a circuit extends from the base of the finger assembly 21 through the conductor 32, the hollow cylindrical contact member 36, the movable contact member 35, the finger assembly 34, the conductor 37, the primary winding 38, the arcing ring 23, contact member 20, the finger assembly 25 and the portion 29 to the terminal bushing 12. Thus, the secondary contact means carries the full amount of the current to the circuit breaker for a short time during an interrupting operation.

A second operating mechanism D is provided for actuating the movable synchronous contact 35, which second mechanism D is independently operable from the first operating mechanism D. The fluid amplifier l5 constituting a part of the second operating mechanism D is of the bistable or wall attachment type. The wall attachment amplifier uses the Coanda effect in its operation. The Coanda effect is the natural attachment of a free jet to an adjacent wall. Thus, a fluid jet between two walls will accelerate and entrain fluid on both sides, but any deflection of the jet towards one wall will cause greater acceleration and consequently a greater pressure reduction on that side. This causes greater inclination of the jet and so on until the jet attaches to the wall creating a low pressure bubble within which fluid circulates. The condition where the jet is centered between walls is an unstable one; the jet will always attach to one wall or another. This is what occurs when power flow is started in the bistable amplifier. The amplifier may be so constructed that the power jet is cocked slightly to one side, for example, to the right, so that initially it attaches to the right wall. The jet can be made to detach from one wall and attach to the other wall by momentarily pressurizing or merely opening to ambient pressure the control port on the attached side so as to increase the pressure in the bubble. The jet remembers" the wall to. which it was last directed even though the outlet port on that side is completely blocked.

An amplifier of another type is the proportional amplifier which differs from the bistable amplifier in that the control ports are actually jets designed to convert control pressure into velocity and the walls of the amplifier are cut-away downstream of the control jet and connected to drain to ensure that wall attachment does not occur. The power jet is deflected through an angle by the control jet. Thus, the direction of flow of the power jet may be controlled by the control jet. In general, amplifiers, of both types may be made by grooving one plate to a constant depth to provide the desired passageways or channels therein and clamping or cementing another plate to it so as to create channels of rectangular cross-section. The plates may be composed of any metallic, plastic, glass, ceramic, or other suitable material.

The fluid amplifier 15, constituting a part of the second operating mechanism D comprises an actuating piston 45 slidably disposed in a cylinder 46 provided in an insulating plate or body 47, passageways 48 and 49 formed in the plate 47 and communicating with opposite sides of the piston 45 in the cylinder 46, a power inlet passageway 51 communicating with a common junction 52 of the passageways 48 and 49, outlet passageways 53 and 54 connected to the oil reservoir 16 through a passageway 55, a return valve 56 and a pipe 57, a

phase accumulator 58 connected to the main accumulator 19 through a heat exchanger coil 59, and control valves 61 and 62 which control the openings to control ports 63 and 64, respectively. A flexible container 65 containing a compressible gas is disposed inside the phase accumulator 58. The container 65 may be connected to a supply of suitable gas, such as air or nitrogen, through an opening 66 in a plug 67 which retains the container 65 in the phase accumulator 58. A pressure gauge (not shown) may be provided to indicate the pressure in container 65. The valves 61 and 62 are biased to the closed position by springs and are opened by repulsion coils 68 and 69, respectively.

The oil in the reservoir 16 may be kept at a predetermined temperature by means of an electric heater 71 controlled by a heater control 72. The pump drive motor 17is so controlled by a pressure switch 73 that the system pressure is maintained between a high and low limit, preferably 3,150 to 2,850 psig. Oil at system pressure is delivered to and drained from the secondary contact actuators, which are at high potential, by non-conducting piping.

Normally, the interior of the actuator or fluid amplifier 15 is kept at system pressure up to the return valve 56 so that the secondary contacts are held closed by system pressure acting on the piston 45 in the cylinder 46. System pressure is maintamed by oil which enters via the heat exchanger coil 59 wound around the phase accumulator 58 and leaving via an orifice 74 which is connected to the oil reservoir 16 through a pipe 75. Thus, there is a small continuous flow of oil to keep the actuator wann and thereby avoid sluggish operation due to high oil viscosity.

When the main contact member 20 begins to open, full phase current flows through the secondary contact member 35 causing current to be induced in a current transformer 76 which energizes a solenoid coil 77 to open the return valve 56. Opening the return valve causes the power jet to discharge into the right passage 48, towards which it is cocked, where it impacts on the right actuator input port and is diverted to the return pipe 57 through the passageways 53, 55 and the return valve 56. Due to the Coanda effect, the jet attaches to the right wall and there is no flow in the left passage 49. Thus, the pressure in the cylinder 46 on the right side of the piston 45 becomes a large fraction, approximately 85 percent of the supply pressure and the pressure on the left side of the piston 45 drops to the return pressure, so that the contacts are held closed by larger than normal force.

The separation of the main contact member 20 from the member 27 causes a rush of current through a synchronous control device 78 and the primary winding 38 of the transformer 39 both of which are energized by the current flowing through the conductor 37. As shown more clearly in FIG. 3, the synchronous control device 78 is of a saturating core reactor type and comprises a magnetic core 79 having an air gap 81 therein. A coil 82 is wound on the core 79. The rapid rate of change of the flux in the core 79 caused by a change in the current flowing through the conductor 37 induces a current in the winding 82. The winding 82 is connected to the repulsion coil 68 on the valve 61 through conductors 83 in series with the contact members of a position switch 84. The switch 84 functions to prevent the device 78 from causing the valve 61 to be opened at the initial rush of current through the secon dary contact means 14 caused by the opening of the main contact means 13.

However, the valve 61 is opened just prior to a current zero after the opening of the main contact members. The core 79 of the device 78 unsaturates as the current in the conductor 37 approaches zero and the rapid rate of change of the flux in the core induces a current in the winding 82 to energize the repulsion coil 68 provided the contact members of the position switch 84 are closed. As shown, the switch 84 is actuated by a cam 85 on the member 26 attached to the main contact member 20. Thus, the cam 85 maybe so located that the switch 84 is closed after the breaker current is transferred to the secondary contacts and after the initial surge of current through the secondary contacts is over.

The energization of the repulsion coil 68 by the synchronous device 78 just prior to current zero causes the valve plate 61, which is also an armature for the coil 68, to be momentarily displaced. This admits oil from apassageway 86 to the control jet 63 causing the power jet from the passageway 51 to switch to the leftwall and flow through the passageway 49 to increase the pressure on the left side of the piston 45 to a large fraction of the supply pressure and reduce the pressure on the right side of the piston to the return pressure, thereby opening the secondary contact member 35.

If the interrupter should fail to interrupt, and pass up current zero, the repulsion coil 69 is energized by current induced in the secondary winding 41 of the saturating core current transformer 39, the primary winding 38 of which is in series with the conductor 37 and is energized by the current flowing through the secondary contact member 35. The current transformer 39 is so constructed that the core saturates a few milliseconds after the fault current goes through zero and remains saturated until the fault current reaches zero again one-half cycle later. As the current reverses, the flux in the core goes to saturation in the other direction, producing an EMF which energizes the repulsion coil 69. Secondary winding 41 of the transformer 39 is connected to the coil 69 through conductors 87 in series with an auxiliary switch 88 actuated by the valve 62. The energization of the coil 69 momentarily opens the valve 62 to admit oil from the passageway 86 to the control jet 64, thereby switching the power jet to the right passageway 48 and reclosing the secondary contact member 35 which is again reopened just prior to the next current zero in the manner hereinbefore described.

The compressed gas in the container 65 inside the phase accumulator 58 is a source of instant power for the actuator. It stores energy which is released to force oil from the accumulator 58 through the passageway 51 to carry out an openreclose-open-reclose operation. The phase accumulator 58 will be replenished in a small fraction of a second from the main accumulator 19, but the transmission time over the oil line between the main accumulator and the phase accumulator, which may be relatively long, precludes using the main accumulator as a source of power in contact actuation.

The alternate scheme, shown in FIG. 2, comprises a bistable first stage amplifier 15', shown dotted, and a second stage amplifier 91 which is of the proportional type. Fluid is admitted to the first stage amplifier 15 from the accumulator 58 through the port 92. The power jet of the first stage amplifier is cocked to the left so that it discharges to return through the passageway 55 initially. The power jet of the proportional second stage amplifier is cocked to the right so that it is directed into the passageway 48' to hold the secondary contact members closed. When the control valve 61 is opened in the manner hereinbefore described, the first stage jet switches to the right wall and flows to a control jet 93 of the second stage amplifier through a port 94. This control jet flow deflects the second stage flow to the left cylinder passageway 49', thereby causing the secondary contact members to open. Energizing the repulsion coil 69' to open the control valve 62 in the manner hereinbefore described causes the system to reverse to the initial condition and reclose the secondary contact members.

From the foregoing description, it is apparent that the invention'provides for the synchronous operation of the contact members of a circuit interrupter. The contact members are opened and reclosed rapidly by means of a fluid amplifier having control valves which are relatively small and light in weight and which may be operated with a smallamount of energy. Provision is made for storing energy in the fluid system to ensure rapid repeat operation of the contact members of the interrupter.

I claim as my invention: 1. In a circuit breaker, in combination, relatively movable main contacts and relatively movable secondary contacts connected in parallel-circuit relation when the breaker is closed, first operating means for effecting opening and closing motions of the relatively movable main contacts, second operating means independently movable of said first operating means and comprising fluid amplifier means for operating the movable secondary contact, pressure-producing means providing a continuous flow of fluid through the fluid-amplifier means, fluid-jet means for changing the flow of fluid to actuate the movable secondary contact, valve means for controlling the fluid-jet means, and synchronous control means for controlling the operation of said valve means.

2. The combination defined in claimv 1, wherein the synchronous-control means is responsive to the current flowing through the secondary contacts.

3. The combination defined in claim 1, including energystorage means supplying energy to the fluid-amplifier means 5. The combination defined in claim 1, including an accumulator receiving fluid from the pressure-producing means, and a compressed gas in said accumulator for supplying energy to the fluid-amplifier means for repeat operations of the movable secondary contact.

6. The combination defined in claim 5, including a flexible container in the accumulator for containing the compressed gas for supplying energy to the fluid-amplifier means during repeat operations of the movable secondary contact.

7. The combination defined in claim 1, wherein the fluidamplifier means has a fluid-actuated piston connected to the movable secondary contact, passageways communicating with opposite sides of said piston, and said passageways having a common junction constructed to normally direct the flow of fluid to maintain the secondary contact closed.

8. The circuit-breaker combination of claim 1, wherein the fluid-amplifier means has a fluid-actuated piston connected to the secondary contacts, passageways communicating with opposite sides of the piston, said passageways having a common junction, a fluid reservoir, pressure-producing means providing a continuous flow of fluid from the reservoir to the junction, said junction being constructed to normally direct the flow of fluid to maintain the contact member in its closed position, fluid-jet means for changing the flow of fluid to cause the piston to actuate the secondary contacts to their open position, electrically-operated valve means controlling the fluidjet means, and means responsive to the current flowing through the secondary contact members for energizing said valve means. r

9. The circuit-breaker combination defined in claim 8, in-

cluding additional fluid-jet means for returning the flow of fluid to its original direction to cause the piston to actuate the contact member to its closed position, additional electricallyoperated valve means controlling the additional fluid-jet means, synchronous-control means for controlling the operation of the first-named valve means, and means responsive to current flowing through the secondary contact members for controlling the operation of said additional valve means.

10. The circuit-breaker combination of claim 8, wherein the fluid-amplifier means comprises a bistable first-stage amplifier and a second-stage amplifier of a proportional type, said second-stage amplifier having the fluid-actuated piston connected to the movable secondary contact member, and said first-stage amplifier having the electrically-operated valve means for controlling the fluid-jet means. 

1. In a circuit breaker, in combination, relatively movable main contacts and relatively movable secondary contacts connected in parallel-circuit relation when the breaker is closed, first operating means for effecting opening and closing motions of the relatively movable main contacts, second operating means independently movable of said first operating means and comprising fluid amplifier means for operating the movable secondary contact, pressure-producing means providing a continuous flow of fluid through the fluid-amplifier means, fluid-jet means for changing the flow of fluid to actuate the movabLe secondary contact, valve means for controlling the fluidjet means, and synchronous control means for controlling the operation of said valve means.
 2. The combination defined in claim 1, wherein the synchronous-control means is responsive to the current flowing through the secondary contacts.
 3. The combination defined in claim 1, including energy-storage means supplying energy to the fluid-amplifier means for repeat operations of the movable secondary contacts.
 4. The combination defined in claim 2, including energy-storage means containing a compressible fluid for supplying energy to the fluid-amplifier means for repeat operations of the movable secondary contact.
 5. The combination defined in claim 1, including an accumulator receiving fluid from the pressure-producing means, and a compressed gas in said accumulator for supplying energy to the fluid-amplifier means for repeat operations of the movable secondary contact.
 6. The combination defined in claim 5, including a flexible container in the accumulator for containing the compressed gas for supplying energy to the fluid-amplifier means during repeat operations of the movable secondary contact.
 7. The combination defined in claim 1, wherein the fluid-amplifier means has a fluid-actuated piston connected to the movable secondary contact, passageways communicating with opposite sides of said piston, and said passageways having a common junction constructed to normally direct the flow of fluid to maintain the secondary contact closed.
 8. The circuit-breaker combination of claim 1, wherein the fluid-amplifier means has a fluid-actuated piston connected to the secondary contacts, passageways communicating with opposite sides of the piston, said passageways having a common junction, a fluid reservoir, pressure-producing means providing a continuous flow of fluid from the reservoir to the junction, said junction being constructed to normally direct the flow of fluid to maintain the contact member in its closed position, fluid-jet means for changing the flow of fluid to cause the piston to actuate the secondary contacts to their open position, electrically-operated valve means controlling the fluid-jet means, and means responsive to the current flowing through the secondary contact members for energizing said valve means.
 9. The circuit-breaker combination defined in claim 8, including additional fluid-jet means for returning the flow of fluid to its original direction to cause the piston to actuate the contact member to its closed position, additional electrically-operated valve means controlling the additional fluid-jet means, synchronous-control means for controlling the operation of the first-named valve means, and means responsive to current flowing through the secondary contact members for controlling the operation of said additional valve means.
 10. The circuit-breaker combination of claim 8, wherein the fluid-amplifier means comprises a bistable first-stage amplifier and a second-stage amplifier of a proportional type, said second-stage amplifier having the fluid-actuated piston connected to the movable secondary contact member, and said first-stage amplifier having the electrically-operated valve means for controlling the fluid-jet means. 